Problem: Solve for $a$ : $2 + a = 29$
Answer: Subtract $2$ from both sides: $ \begin{eqnarray} \\ 2 + a &=& 29 \\ \\ {-2} && {-2} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{2 + a} &\hphantom{=}& \hphantom{29} \\ a &=& 29 {- 2} \\ \end{eqnarray} $ Simplify. $ a = 27$